Typically, a solid oxide fuel cell (sometimes abbreviated as SOFC hereinafter) is supplied with a hydrogen-containing gas (reformed gas) produced by reforming a hydrocarbon-based fuel, such as kerosene and city gas, at a reformer. The SOFC generates electric power by electrochemical reaction of the reformed gas and air. The SOFC typically operates at a high temperature approximately ranging from 550° C. to 1000° C.
There are various types of reforming reaction, such as steam reforming and partial oxidation reforming. In particular, the steam reforming is most commonly used because the reformed gas produced by the steam reforming contains a high concentration of hydrogen. The steam reforming is an extremely highly endothermic reaction and requires a relatively high reaction temperature of about 550° C. to 750° C. and therefore a high temperature heat source. Therefore, an indirect internal reforming SOFC has been developed that is provided with a reformer disposed in the vicinity of the SOFC (at a location where the reformer receives thermal radiation from the SOFC) so that the reformer is heated by the radiation heat from the SOFC. In particular, an indirect internal reforming SOFC burns the anode off gas containing a combustible component (gas discharged from the anode of the SOFC) in a container (module container) of the indirect internal reforming SOFC and uses the combustion heat as a heat source to heat the reformer (Patent Document 1).
Reforming catalysts having various kinds of structure, such as a granular catalyst (Patent Document 2) and honeycomb-type catalysts (Patent Documents 3 and 4), are known. Among others, the granular catalyst is relatively inexpensive and widely used.    Patent Document 1: Japanese Patent Laid-Open No. 2004-319420    Patent Document 2: Japanese Patent Laid-Open No. H5-129026    Patent Document 3: Japanese Patent Laid-Open No. 2004-269332    Patent Document 4: Japanese Patent Laid-Open No. 2006-327904